Corn (monocot) and soybeans (dicot), for example, can be rotated in various crop rotation cycles in various geographies. Cotton is also a dicot.
“Volunteer” plants are unwanted plants from the prior growing season that emerge in a field planted with crops for the current growing season. Volunteers are basically weeds, and can, like weeds, reduce harvest and yield of the crop of interest for the current growing season. The volunteers divert fertilizer resources and the like from the desired crops.
Unlike plain weeds, volunteers are often specifically engineered to be resistant to some herbicides. Thus, controlling volunteers can be more difficult than controlling naturally occurring weeds.
AAD (aryloxy alkanoate dioxygenase) genes as described herein impart high levels of tolerance to 2,4-D herbicides in plants that are transformed with an AAD gene.
AAD-1 genes also impart high levels of tolerance to phenoxy- and aryloxyphenoxyproplonate herbicides (“fops” such as fluazifop and haloxyfop). (AAD-1 genes are described in WO 2007/053482.) Thus, AAD-1 allows the use of some fops as either selection agents or as herbicides on crops where crop destruction would be expected without the AAD-1 gene.
AAD-12 and AAD-13 genes also impart high levels of tolerance to pyridyloxyacetate herbicides (such as triclopyr and fluroxypyr; “pyrs”) to soybeans and other dicot species transformed with the gene. Thus, AAD-12 and AAD-13 each allow the use of pyrs as either selection agents or as herbicides on crops where crop destruction would be expected without the AAD-12 or AAD-13 gene.
There are very numerous dicot-only herbicides that kill dicots, or selective dicots.